The spine, also called the vertebral column or backbone, provides a strong, flexible support for the head and trunk. It also protects the spinal cord and serves as a point of attachment for the ribs, pelvis and muscles of the back. Usually accounting for about two fifths of the total height of the body, called vertebrae, piled one upon another.

These are named according to the position they occupy, there are 7 cervical or neck, 12 thoracic or chest, 5 lumbar or loin, 5 sacral or fused to form the sacrum and usually 4 coccygeal or fused to form the coccyx, or tailbone vertebrae. Between the sacrum and the hip bone or ilium is the sacroiliac joint, which transmits the body's weight to the legs.

Running through the central canal formed by the stacked vertebrae from the base of the brain to the first lumbar vertebra is the spinal cord. This cylinder of nerve tissue is an extension of the brain and acts as the main route for sensory information passing between the brain and the body.

Along the length of the spinal cord, 31 pairs of nerves branch out through openings between the vertebrae called foramina. These nerves carry commands from the brain to organs and muscles, as well as messages about temperature, touch and pain back to the spinal cord and brain.

The spine is made up to 33 vertebrae stacked on top of each other. Running through its center, protected by the surrounding bone, is the spinal cord which is the primary route for signals between the body and the brain. The normal spine curves naturally in an S shape, in at the neck, out at the shoulders, in again at waist level and outwards at the base.

This shape makes the spine flexible and able to withstand the stresses and strains of everyday life.